[QUOTE=pmax;9991294]Rule out your AFM ! Take it apart or if that's not an option, perhaps you can find another gear/rpm combination which exhibits the same stumble and confirm it's the AFM.
Not my thread but this looks applicable.
http://forums.pelicanparts.com/porsche-911-technical-forum/786163-3-2-engine-stumble-miss.html
Thanks for sharing the thread pmax , I changed the wiper track last week but this time I will clean it . I'll let you know how it works out .